Various kinds of lens holder driving apparatuses have been proposed which are capable of obtaining a sharp image by preventing image blurring on an image forming plane even when camera-shake (vibration) occurs at the time of capturing of an image.
While various kinds of schemes have been proposed as a camera-shake correcting scheme, among these, a “barrel shifting scheme” is known. Here, the “barrel shifting scheme” is a scheme for correcting camera-shake by moving (a lens holder holding) a lens barrel itself housed in an auto-focusing (AF) lens holder driving section (AF unit) in a direction perpendicular to an optical axis direction with respect to a fixed section (base member). A lens holder driving apparatus adopting such a “barrel shifting scheme” includes a lens holder driving apparatus adopting a “moving magnet scheme” in which a permanent magnet moves (is movable) and a lens holder driving apparatus adopting a “moving coil scheme” in which a drive coil moves (is movable).
In the lens holder driving apparatus adopting such a “barrel shifting scheme,” a permanent magnet for an AF lens holder driving section is also used as a permanent magnet for a camera-shake correcting section to realize reduction in size and height.
For example, PTL 1 discloses a lens holder driving apparatus adopting a “moving magnet scheme.” The lens holder driving apparatus disclosed in PTL 1 has an auto-focusing lens holder driving section (AF unit) which causes a lens holder holding a lens barrel to move along an optical axis, and a camera-shake correcting section which corrects camera-shake by moving the AF unit in a first direction and a second direction with respect to a fixed section, the first direction and the second direction being orthogonal to the optical axis and orthogonal to each other.
In the lens holder driving apparatus disclosed in PTL 1, the AF unit includes a focus coil fixed at the lens holder, a permanent magnet composed of a plurality of permanent magnet pieces having first faces facing the focus coil, a magnet holder holding the permanent magnet, and first and second leaf springs supporting the lens holder so as to make the lens holder displaceable in the optical axis direction. The fixed section is disposed in proximity to the second leaf spring. The camera-shake correcting section has a supporting member supporting the AF unit in such a manner that the AF unit can rock with respect to the fixed section, a camera-shake correction coil (FP coil) composed of a plurality of camera-shake correction coil portions disposed so as to respectively face second faces perpendicular to the first faces of the plurality of permanent magnet pieces, and a plurality of Hall devices.
In the lens holder driving apparatus disclosed in PTL 1, an imaging device disposed on an imaging substrate is mounted at a lower part of the fixed section. The fixed section is configured with a base, a coil substrate having a circular opening and a flexible printed-circuit (FPC) board. The coil substrate is disposed so as to face the permanent magnet with a gap therebetween. The coil substrate is attached to the base across the flexible printed-circuit (FPC) board. The camera-shake correction coil is formed on the coil substrate. Interconnection of the flexible printed-circuit (FPC) board is electrically connected to a plurality of lands of the coil substrate. Therefore, a current is supplied to the camera-shake correction coil via the flexible printed-circuit (FPC) board.
In the lens holder driving apparatus disclosed in PTL 1, the base has a ring-shaped inner wall at a central inner diameter portion thereof. This inner wall of the base covers and hides an inner peripheral side wall which defines the circular opening of the coil substrate, thereby preventing collision between the inner peripheral side wall which defines the circular opening of the coil substrate and the lens barrel, and prevents generation of relatively large dust due to the coil substrate being scraped.
In the lens holder driving apparatus having such a structure, to perform camera-shake correction when an image is captured, the AF unit is driven in a direction which cancels out camera-shake. This drive force can be obtained by making a current flow through the camera-shake correction coil (FP coil) in a magnetic field created by the permanent magnet. Therefore, upon camera-shake correction, a current for pulse-width modulated (PWM) drive necessary for camera-shake correction is made to flow through the camera-shake correction coil (FP coil) and the flexible printed-circuit (FPC) board.